Fairchild SLTS218B service manual

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PTB48500, PTB48501, PTB48502

Dual-Output, 48-V Input Isolated
DC/DC Converter for xDSL

Description

The PTB4850x power modules are a
dual-output isolated DC/DC converter,
designed to provide the logic supply volt­ages for AC-7 based xDSL applications.
The PTB48500 is rated for 13 A of total
output current, making it suitable for
32-channel xDSL applications. The
PTB48501 and PTB48502 provide output
current for powering up to 64 xDSL chan­nels. The PTB48501 is rated for 16.5 A
total output current, and the PTB48502,
21 A. The PTB48502 incorporates 10 W
of additional capacity for powering periph­eral circuitry. Any of these converters can
be used for other applications with simi­lar power requirements.

The modules operate from a standard
telecom (-48 V) central office (CO) supply
and include an “on/off” enable control,

SLTS218B - SEPTEMBER 2003 - REVISED NOVEMBER 2004

Features

• Dual Outputs

(Independently Regulated)

• Input Voltage Range:

36 V to 75 V

• Power-up/Down Sequencing

• 1500 VDC Isolation

• Over-Current Protection

• Over-Temperature Shutdown

• Under-Voltage Lockout

output current limit, over-temperature
protection, input under-voltage lockout
(UVLO). The PTB48500 and PTB48501
also incorporates a power-up reset (POR)
output.

The modules are designed to operate
with one of the PTB4851x DC/DC con­verter modules. The combination of a
PTB4850x and PTB4851x converter
provides the complete the power supply
for an AC7 chipset. The “EN Out” and
“Sync Out” pins provide compatible out­put signals for controlling both the power
up sequence and switching frequency of
the PTB48510.

The PTB4850x modules employ
double-sided surface mount construction,
and are an industry standard size.

• Fixed Frequency Operation

• Temp Range: –40 to 100 °C

• Industry Standard Outline

• Operates with PTB4851x for

Complete AC7 Power Solution

• Powers up to 64 DSL Ports

• Safety Approvals:

UL/cUL 60950
EN 60950

Pin Configuration

Pin Function

1+V

I

2 Sync Out
3 Enable #
4 EN Out
5–V

I

6+VO 2
7 COM
8 POR* / COM †
9Vo2 Adjust
10 +VO 1

Shaded functions indicate signals
that are referenced to –VI.

# Denotes positive logic:

Open = Normal operation
–V

= Outputs Off

I

* Denotes negative logic:

High = Normal operation
Low = Reset

† This pin is COM on the PTB48502

Stand-Alone Application

+V

I

–V

I

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1

5

3

+V

–V

Enable

Sync Out

I

PTB4850x

I

EN Out

POR

Vo

Vo

Vo

Adj

2

COM

1

2

2
4

* Pin 8 is ‘COM’ on PTB48502

(8) *

Vo

Vo

COM

1

2

10

6

9

7, (8) *

L
O
A
D

L
O
A
D

PTB48500, PTB48501, PTB48502

Dual-Output, 48-V Input Isolated
DC/DC Converter for xDSL

Ordering Information

Base Part No. (PTB4850❒xxx)

Order Prefix Description

PTB48500xxx 13 A (32-Ports)
PTB48501xxx 16.5 A (48/64-Ports)
PTB48502xx 21 A (64-Ports + 10 W)

Notes: (1) Reference the applicable package reference drawing for the dimensions and PC board layout

(2) “Standard” option specifies 63/37, Sn/Pb pin solder material.

Output Voltage

Code Voltage

A 3.3 V / 1.2 V

(PTB4850x❒xx)

Pin Descriptions

+VI: The positive input supply for the module with respect

. When powering the module from a –48 V telecom

to –V

in

central office supply, this input is connected to the primary
system ground.

–V

: The negative input supply for the module, and the

I

0 VDC reference for the ‘Enable’, ‘EN Out’, and ‘Sync
Out’ signals. When the module is powered from a +48-V

supply, this input is connected to the 48-V Return.

V

1: The higher regulated power output voltage, which

O

is referenced to the COM node.

V

2: The lower regulated power output voltage, which

0

is referenced to the COM node.

COM: The secondary return reference for the module’s two
regulated output voltages. It is dc isolated from the input
supply pins.

V

2 Adjust: Using a single resistor, this pin allows Vo2 to

O

be adjusted higher or lower than the preset value. If not
used, this pin should be left open circuit.

Enable: This is an open-collector (open-drain) positive
logic input that enables the module output. This pin is
referenced to -Vin. A logic ‘0’ at this pin disables the
module’s outputs, and a high impedance enables the out­puts. If not used the pin should be left unconnected.

EN Out: This open-collector output may be used to enable
the output of other DC/DC converters in applications
where the power-up sequence of the related voltages must
be precisely controlled. The output is used principally to
control the startup up of a PTB4851xx module when
powering ADSL circuits based on the AC7 chipset. The
signal is referenced to -Vin, and is active low. It is initially
‘off’ (high impedance), and turns ‘on’ when the output
voltage, Vo

Sync Out: The signal generated by this pin is designed to
be used exclusively with the PTB48510 in AC7 ADSL
applications. When the ‘Sync Out’ of this converter is
connected directly to the ‘Sync In’ pin of the PTB48510,
both modules will operate at the same switch conversion
frequency.

POR*: (Available to PTB48500 and PTB48501 only!)
This pin produces an active-low power-on reset signal
that may be used to reset logic circuitry. The output is
set low during power up just as the output voltage from
Vo

starts to rise. It remains low for 10 ms after the volt-

1

age at Vo1 has reached its nominal set-point voltage.
This signal is referenced to the COM node, and has a

3.3-kΩ internal pull-up resistor to Vo

SLTS218B - SEPTEMBER 2003 - REVISED NOVEMBER 2004

Package Options

Code Description Pkg Ref.

AH Horiz. T/H (ERH)
AS SMD, Standard

, has risen to its nominal set-point voltage.

1

(PT4850xx❒❒)

(2)

1

(ERJ)

.

(1)

Environmental and General Specifications (Unless otherwise stated, all voltages are with respect to –V

Characteristics Symbols Conditions Min Typ Max Units

Input Voltage Range V
Isolation Voltage Input–output/input–case 1500 — — V

Capacitance Input to output — 1500 — pF
Resistance Input to output 10 — — MΩ

Operating Temperature Range T
Over-Temperature Protection OTP Shutdown threshold — 115 —

Solder Reflow Temperature T
Storage Temperature T
Mechanical Shock Per Mil-STD-883D, Method 2002.3

Mechanical Vibration Mil-STD-883D, Method 2007.2 Suffix H — 20 —

Weight — — 20 — grams
Flammability — Meets UL 94V-O

Notes: (i) During reflow of SMD package version do not elevate peak temperature of the module, pins or internal components above the stated maximum.

in

a

reflow

s

Over output load range 36 48 75 VDC

Over Vin Range –40 — +85 °C

Hysterisis — 10 —
Surface temperature of module body or pins 235
— –40 — 125 °C

1 msec, ½ Sine, mounted

20-2000 Hz Suffix C — 5 —

— 500 — G’s

For technical support and further information visit http://power.ti.com

)

in

(i)

°C

°C

G’s

PTB48500

Dual-Output, 48-V Input Isolated
DC/DC Converter for xDSL

Specifications (Unless otherwise stated, T

=25°C, VI =48 V, CI =0µF, CO =0 µF, and IO =50% Iomax)

A

SLTS218B - SEPTEMBER 2003 - REVISED NOVEMBER 2004

PTB48500A

Characteristic Symbol Conditions Min Typ Max Units

Output Power Po

Output Current Io

Output Voltage Vo
Temperature Variation ∆Reg

Line Regulation ∆Reg
Load Regulation ∆Reg
Cross Regulation ∆Reg

Efficiency η Io
Vo Ripple (pk-pk) V

Transient Response t

Over Current Threshold Iotrip VI =36 V,

, Po

1

Po

total

, Io

1

Io1 + Io

1

Vo

2

r

tr

∆V

tr

temp

line

load

cross

2

Both outputs — — 28 W

2

Over VI range Vo1 (3.3 V) 0 — 6

Total (both outputs) 0 — 13 A

2

Inlcudes set point, line, load, 3.2 3.3 3.4
–40 ≤ TA ≤ +85°C 1.16 1.2 1.24

–40° ≤TA ≤ +85°C, I

Over VI range Vo1, Vo
Over IO range Vo1, Vo
I

min ≤ Io2 ≤ I

O

I

min ≤ Io1 ≤ I

O

, Io2 =Iomax — 82 — %

1

20 MHz bandwidth Vo

1 A/µs load step, 50% to 100% Iomax — 30 — µs
Vo1, Vo2 over/undershoot — ±2.0 — %V

reset followed by auto-recovery

=IO min Vo

O

max, Io

=1 A ∆Vo

o

1

max, Io

=1 A ∆Vo

o

2

Vo1 (3.3 V) — — 19.8
Vo2 (1.2 V) — — 8.4

Vo2 (1.2 V) 0 — 7

— ±0.5 —

1

Vo

— ±0.8 —

2

— ±1 ±10 mV

2

— ±3 ±12 mV

2

——10

1

——10

2

—2050

1

Vo

—2050

2

Io

1

+ Io

13.5 16 — A

2

(1)
(1)

Output Voltage Adjust Range Vadj Vo2 only -10 — +20 %V
Switching Frequency ƒ
Under-Voltage Lockout VI on VI increasing — 34 —

On/Off Enable (pin 3) Referenced to –VI (pin 5)
Input High Voltage V
Input Low Voltage V

Input Low Current I

s

VI off VI decreasing — 32 —

IH
IL

IL

Over VI and IO ranges 500 550 600 kHz

+3.6 — +75
–0.2 — +0.8

(2)

—–1—mA
Standby Input Current II standby pins 3 & 5 connected — 2 — mA
Internal Input Capacitance C
External Output Capacitance Co

Reliability MTBF Per Telcordia SR-332

Notes: (1) See Safe Operating Area curves or contact the factory for the appropriate derating.

(2) The On/Off Enable (pin 3) has an internal pull-up and may be controlled with an open-collector (or open-drain) transistor. The input is diode protected

and may be connected to +VI. The maximum open-circuit voltage is 7 V. If it is left open circuit the converter will operate when input power is applied.

Co

I

1
2

50% stress, TA =40°C, ground benign

—2 —µF

(3)

0

0

(3)

— 5,000
— 5,000

1.5 — — 10

(3) An output capacitor is not required.

W

A

V

%V

mV

mV

V

V

µF

6

o

pp

o

o

Hrs

For technical support and further information visit http://power.ti.com

PTB48500

Typical Characteristics

Dual-Output, 48-V Input Isolated
DC/DC Converter for xDSL

PTB48500A Characteristic Data (See Note A)

Efficiency vs Load Current (See Note B)

100

90

80

70

Efficiency - %

60

50

024681012

Power Dissipation vs Load Current (See Note B)

10

8

6

4

Pd - Watts

Io1 + Io2 (A)

SLTS218B - SEPTEMBER 2003 - REVISED NOVEMBER 2004

Safe Operating Area PTB48500A (See Note C)

V

=48 VDC (See Note B)

IN

90

80

V

IN

48 V
36 V
75 V

V

IN

48 V
36 V
75 V

70

60

50

40

Ambient Temperature (°C)

30

20

0 5 10 15 20 25 30

Total Output Power (W)

Airflow

400LFM
200LFM
100LFM
Nat Conv

2

0

024681012

Cross Regulation,

6

4

(mV)

o

2

0

-2

Cross Regulation ∆V

-4

-6
01234567

Io1 + Io2 (A)

∆∆

∆Vo

vs Ioy @Iox =1 A & VIN =48 V

∆∆

x

Io1 : Io2 (A)

Vo1 vs Io
Vo2 vs Io

2
1

Note A: Characteristic data has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: Load current is increased proportionally from both outputs, up to the respective maximum value of each output.
Note C: SOA curves represent the conditions at which internal components are at or below the manufacturer’s maximum operating temperatures. Derating limits apply to

modules soldered directly to a 4 in. × 4 in. double-sided PCB with 1 oz. copper.

For technical support and further information visit http://power.ti.com

PTB48501

Dual-Output, 48-V Input Isolated
DC/DC Converter for xDSL

Specifications (Unless otherwise stated, T

=25°C, VI =48 V, CI =0 µF, CO =0 µF, and Io =50% IO max)

A

SLTS218B - SEPTEMBER 2003 - REVISED NOVEMBER 2004

PTB48501A

Characteristic Symbol Conditions Min Typ Max Units

Output Power Po

Output Current Io1, Io

Output Voltage Vo
Temperature Variation ∆Reg

Line Regulation ∆Reg
Load Regulation ∆Reg
Cross Regulation ∆Reg

Efficiency η Io
Vo Ripple (pk-pk) V

Transient Response t

Over Current Threshold IO trip VI =36V,

, Po

1

Po

total

Io1 + Io

1

Vo

2

r

tr

∆V

tr

temp

line

load

cross

2

Both outputs — — 32.4 W

2

Over VI range Vo1 (3.3 V) 0 — 6

Total (both outputs) 0 — 16.5 A

2

Inlcudes set point, line, load, 3.2 3.3 3.4
–40 ≤ TA ≤ +85°C 1.16 1.2 1.24

–40° ≤TA ≤ +85°C, I

Over VI range Vo1, Vo
Over Io range Vo1, Vo
I

min ≤ Io2 ≤ I

O

I

min ≤ Io1 ≤ I

O

, Io2 =Iomax — 81 — %

1

20 MHz bandwidth Vo

1 A/µs load step, 50% to 100% Iomax — 30 — µs
Vo1, Vo2 over/undershoot — ±2.0 — %V

reset followed by auto-recovery

=IO min Vo

O

max, Io

=1 A ∆Vo

o

1

max, Io

=1 A ∆Vo

o

2

Vo1 (3.3 V) — — 19.8
Vo2 (1.2 V) — — 12.6

(1)

Vo2 (1.2 V) 0 — 10.5

— ±0.5 —

1

Vo

— ±0.8 —

2

— ±1 ±10 mV

2

— ±3 ±12 mV

2

——10

1

——10

2

—2050

1

Vo

—2050

2

Io

1

+ Io

—24—A

2

(1)

Output Voltage Adjust Range Vadj Vo2 only –20 — +10 %V
Switching Frequency ƒ
Under-Voltage Lockout V

On/Off Enable (pin 3) Referenced to –VI (pin 5)
Input High Voltage V

Input Low Voltage V

Input Low Current I

s

on VI increasing — 34 —

I

VI off VI decreasing — 32 —

IH
IL

IL —–1—mA

Over VI and IO ranges 500 550 600 kHz

+3.6 — +75
–0.2 — +0.8

(2)

Standby Input Current II standby pins 3 & 5 connected — 2 — mA
Internal Input Capacitance C
External Output Capacitance Co

Reliability MTBF Per Telcordia SR-332

Notes: (1) See Safe Operating Area curves or contact the factory for the appropriate derating.

(2) The On/Off Enable (pin 3) has an internal pull-up and may be controlled with an open-collector (or open-drain) transistor. The input is diode protected

and may be connected to +VI. The maximum open-circuit voltage is 7 V. If it is left open circuit the converter will operate when input power is applied.

Co

I

1
2

50% stress, TA =40°C, ground benign

—2 —µF

(3)

0
0

(3)

— 5,000
— 5,000

1.5 — — 10

(3) An output capacitor is not required.

W

A

V

%V

mV

mV

V

V

µF

6

o

pp

o

o

Hrs

For technical support and further information visit http://power.ti.com